Conventional image forming apparatus such as a copying machine, a scanner, and a facsimile machine may include an image reading device configured to read an image of an original. As the image reading device, there is known an image reading device configured to read an image of an original by an image reading portion while conveying the original by an automatic original feeder (auto document feeder (ADF)).
On the other hand, the image forming apparatus forms an image based on information on the image that is read by the image reading device. For example, when forming images on both surfaces of a sheet, an image forming portion forms an image on one surface (first surface) of the sheet, and then the sheet is conveyed to a sheet re-conveying path so that the sheet is re-conveyed to the image forming portion. The image forming portion then forms an image on an opposite surface (second surface) of the sheet.
There is proposed such a configuration that the sheet re-conveying path of the image forming apparatus is shared with an original conveying path of the image reading device and the image reading portion is arranged in the sheet re-conveying path (PTL 1). When reading an image of an original in the configuration, the original is conveyed to the sheet re-conveying path of the image forming apparatus, and the image reading portion reads the image of the original.
In the apparatus disclosed in PTL 1, however, the width of the image forming apparatus is large in a horizontal direction thereof. Specifically, even when the sheet re-conveying path of the image forming apparatus is shared with the original conveying path of the image reading device so as to downsize the image forming apparatus, the width of the image forming apparatus increases under the mere arrangement of the image reading portion in the sheet re-conveying path. As a result, the image forming apparatus cannot be downsized efficiently.